An icon (from Greek εἰκών eikōn "image") is a religious work of art, most commonly a painting, from Eastern Orthodox Christianity and Catholicism. More broadly the term is used in a wide number of contexts for an image, picture, or representation; it is a sign or likeness that stands for an object by signifying or representing it either concretely or by analogy, as in semiotics; by extension, icon is also used, particularly in modern culture, in the general sense of symbol — i.e. a name, face, picture, edifice or even a person readily recognized as having some well-known significance or embodying certain qualities: one thing, an image or depiction, that represents something else of greater significance through literal or figurative meaning, usually associated with religious, cultural, political, or economic standing.Throughout history, various religious cultures have been inspired or supplemented by concrete images, whether in two dimensions or three. The degree to which images are used or permitted, and their functions — whether they are for instruction or inspiration, treated as sacred objects of veneration or worship, or simply applied as ornament — depend upon the tenets of a given religion in a given place and time.In Eastern Christianity and other icon-painting Christian traditions, the icon is generally a flat panel painting depicting a holy being or object such as Jesus, Mary, saints, angels, or the cross. Icons may also be cast in metal, carved in stone, embroidered on cloth, painted on wood, done in mosaic or fresco work, printed on paper or metal, etc. Creating free-standing, three-dimensional sculptures of holy figures was resisted by Christians for many centuries, out of the belief that daimones inhabited pagan sculptures, and also to make a clear distinction between Christian and pagan art. To this day, in obedience to the commandment not to make "graven images", Orthodox icons may never be more than three-quarter bas relief. Comparable images from Western Christianity are generally not described as "icons", although "iconic" may be used to describe a static style of devotional image.

Iconography (from Greek: εικoνογραφία) refers to the making and liturgical use of icons, pictorial representations of Biblical scenes from the life of Jesus Christ, historical events in the life of the Church, and portraits of the saints. Icons are usually two-dimensional images and may be made of paint, mosaic, embroidery, weaving, carving, engraving, or other methods. A person who practices the art of iconography is called an iconographer.Images have always been a vital part of the Church, but their place was the subject of the Iconoclast Controversy in the 8th and 9th centuries, especially in the East. The Sunday of Orthodoxy, the first Sunday of the Great Fast (Lent) every year celebrates the reestablishment of the Orthodox veneration of icons. The use of iconography is considered one of the most distinctive elements of the Byzantine Rite.

After adoption of Christianity as the only permissible Roman state religion under Theodosius I, Christian art began to change not only in quality and sophistication, but also in nature. This was in no small part due to Christians being free for the first time to express their faith openly without persecution from the state, in addition to the faith spreading to the non-poor segments of society. Paintings of martyrs and their feats began to appear, and early writers commented on their lifelike effect, one of the elements a few Christian writers criticized in pagan art — the ability to imitate life. The writers mostly criticized pagan works of art for pointing to false gods, thus encouraging idolatry. Statues in the round were avoided as being too close to the principal artistic focus of pagan cult practices, as they have continued to be (with some small-scale exceptions) throughout the history of Eastern Christianity.Nilus of Sinai, in his Letter to Heliodorus Silentiarius, records a miracle in which St. Plato of Ankyra appeared to a Christian in a dream. The Saint was recognized because the young man had often seen his portrait. This recognition of a religious apparition from likeness to an image was also a characteristic of pagan pious accounts of appearances of gods to humans, and was a regular topos in hagiography. One critical recipient of a vision from Saint Demetrius of Thessaloniki apparently specified that the saint resembled the "more ancient" images of him - presumably the seventh century mosaics still in Hagios Demetrios. Another, an African bishop, had been rescued from Arab slavery by a young soldier called Demetrios, who told him to go to his house in Thessaloniki. Having discovered that most young soldiers in the city seemed to be called Demetrios, he gave up and went to the largest church in the city, to find his rescuer on the wall.During this period the church began to discourage all non-religious human images - the Emperor and donor figures counting as religious. This became largely effective, so that most of the population would only ever see religious images and those of the ruling class. The word icon referred to any and all images, not just religious ones, but there was barely a need for a separate word for these.

Icons are used particularly in Eastern Orthodox, Oriental Orthodox, and Eastern ( Byzantine rite ) Catholic churches.The Eastern Orthodox view of the origin of icons is quite different from that of secular scholars and from some in contemporary Roman Catholic circles: "The Orthodox Church maintains and teaches that the sacred image has existed from the beginning of Christianity", Léonid Ouspensky has written. Accounts that some non-Orthodox writers consider legendary are accepted as history within Eastern Orthodoxy, because they are a part of church tradition. Thus accounts such as that of the miraculous "Image Not Made by Hands", and the weeping and moving "Mother of God of the Sign" of Novgorod are accepted as fact: "Church Tradition tells us, for example, of the existence of an Icon of the Savior during His lifetime (the "Icon-Made-Without-Hands") and of Icons of the Most-Holy Theotokos [Mary] immediately after Him."Eastern Orthodoxy further teaches that "a clear understanding of the importance of Icons" was part of the church from its very beginning, and has never changed, although explanations of their importance may have developed over time. This is due to the fact that iconography is rooted in the theology of the Incarnation (Christ being the eikon of God) which didn't change, though its subsequent clarification within the Church occurred over the period of the first seven Ecumenical Councils. Also, icons served as tools of edification for the illiterate faithful during most of the history of Christendom.Eastern Orthodox find the first instance of an image or icon in the Bible when God made man in His own image (Septuagint Greek eikona), in Genesis 1:26-27. In Exodus, God commanded that the Israelites not make any graven image; but soon afterwards, he commanded that they make graven images of cherubim and other like things, both as statues and woven on tapestries. Later, Solomon included still more such imagery when he built the first temple. Eastern Orthodox believe these qualify as icons, in that they were visible images depicting heavenly beings and, in the case of the cherubim, used to indirectly indicate God's presence above the Ark.In the Book of Numbers it is written that God told Moses to make a bronze serpent, Nehushtan, and hold it up, so that anyone looking at the snake would be healed of their snakebites. In John 3, Jesus refers to the same serpent, saying that he must be lifted up in the same way that the serpent was. John of Damascus also regarded the brazen serpent as an icon. Further, Jesus Christ himself is called the "image of the invisible God" in Colossians 1:15, and is therefore in one sense an icon. As people are also made in God's images, people are also considered to be living icons, and are therefore "censed" along with painted icons during Orthodox prayer services.According to John of Damascus, anyone who tries to destroy icons "is the enemy of Christ, the Holy Mother of God and the saints, and is the defender of the Devil and his demons." This is because the theology behind icons is closely tied to the Incarnational theology of the humanity and divinity of Jesus, so that attacks on icons typically have the effect of undermining or attacking the Incarnation of Jesus himself as elucidated in the Ecumenical Councils.The Eastern Orthodox teaching regarding veneration of icons is that the praise and veneration shown to the icon passes over to the archetype (Basil of Caesarea,On the Holy Spirit 18:45: "The honor paid to the image passes to the prototype"). Thus to kiss an icon of Christ, in the Eastern Orthodox view, is to show love towards Christ Jesus himself, not mere wood and paint making up the physical substance of the icon. Worship of the icon as somehow entirely separate from its prototype is expressly forbidden by the Seventh Ecumenical Council; standard teaching in the Eastern Orthodox and Roman Catholic churches alike conforms to this principle. The Catholic Church accepts the same Councils and the canons therein which codified the teaching of icon veneration.The Latin Church of the West, which after 1054 was to become known separately as the Roman Catholic Church, accepted the decrees of the iconodule Seventh Ecumenical Council regarding images. There is some minor difference, however, in the Catholic attitude to images from that of the Orthodox. Following Gregory the Great, Catholics emphasize the role of images as the Biblia Pauperum, the "Bible of the Poor," from which those who could not read could nonetheless learn. This view of images as educational is shared by most Protestants.Catholics also, however, accept in principle the Eastern Orthodox veneration of images, believing that whenever approached, sacred images are to be reverenced. Though using both flat wooden panel and stretched canvas paintings, Catholics traditionally have also favored images in the form of three-dimensional statuary, whereas in the East statuary is much less widely employed.

"Written" or "painted"?The most literal translation of the word Greek: εικονογραφία (eikonographia) is "image writing," leading many English-speaking Orthodox Christians to insist that icons are not "painted" but rather "written." From there, further explanations are given that icons are to be understood in a manner similar to Holy Scripture—that is, they are not simply artistic compositions but rather are witnesses to the truth the way Scripture is. Far from being imaginative creations of the iconographer, they are more like scribal copies of the Bible.While the explanation of the purpose and nature of icons is certainly true and consistent with the Church's Holy Tradition, there is a linguistic problem with the insistence on the word written rather than painted. In Greek, a painted portrait of anyone is also a γραφή (graphi), and the art of painting itself is called ζωγραφική (zographiki) while any drawing or painting can be referred to as ζωγραφιά (zographia). Ancient Greek literally uses the same root word to refer to the making of portraits and the making of icons, but distinguishes whether it is "painting from life" (ζωγραφιά) or "painting icons" (εικονογραφία). Thus, from a linguistic point of view, either all paintings—whether icons or simple portraits—are "written" or (more likely) "painted" is a perfectly usable English translation, simply making a distinction between the painting appropriate for icons and that appropriate for other kinds of painting, just as Greek does.Some have suggested that icon writing be used because of the fact that for many centuries, (whether the early Church, the persecutions against the Christians by the pagan authorities, or more recently around the Orthodox World when the faithful have been subjected to non-Orthodox authority), icons were the books of the illiterate and through the depiction of an often simple image refer to and confirm the fundamental belief of the Church; the Incarnation. God's becoming human, his undertaking and sanctifying of human nature and matter in general means that He can be depicted using matter.